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Finding the Fourth Proportional to 620.98, 856.79 and 399.85

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Solution

The fourth proportional to 620.98, 856.79 and 399.85 is: 551.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.98 : 856.79 = 399.85 : x
  2. Step 2: Convert to fraction form
    620.98/856.79 = 399.85/x
  3. Step 3: Cross multiply
    620.98x = 856.79 × 399.85
  4. Step 4: Simplify right side
    620.98x = 342,585.48
  5. Step 5: Solve for x
    x = 342,585.48/620.98
  6. Step 6: Final answer
    x = 551.69

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.